1. Field of the Invention
The present invention relates generally to an apparatus and method for supporting Quality of Service (QoS) in a wideband wireless communication system, and in particular, to an apparatus and method for supporting packet distribution and QoS in a wideband wireless communication system using multiple Frequency Allocations (FAs).
2. Description of the Related Art
Mobile communication technologies are expected to achieve high-speed data communication in order to satisfy future demands of mobile communication users. To this end, high-speed data communication must be supported in a wireless link. A wide bandwidth is required to provide the high-speed data communication in the wireless link, while a time occupied by one symbol becomes significantly short. When one symbol is transmitted along two different paths, a time for delivering the symbol may vary since multiple paths exist in the wireless link. A signal, which includes one symbol and is delivered along a relatively longer path, causes interference to a signal that includes a next symbol and is delivered along a shorter path. Such an Inter-Symbol Interference (ISI) becomes more significant when faster data communication is provided in the wireless link. To address this problem, an Orthogonal Frequency Division Multiplexing (OFDM) technique is used in which a frequency band is divided into several sub-channels, and data streams are separately transmitted through the respective sub-channels.
Meanwhile, a standard or a similar protocol is being modified so that a communication system evolves, to provide a high-speed data service compared to a legacy system, or to address an implementation issue. In such a system evolution process, various systems may be present together in the same area according to a compatibility level with respect to the legacy system. For example, a new system, which uses a Frequency Allocation (FA) of 20 MHz and is further evolved from the legacy system using an FA of 10 MHz, may be installed in an area where an OFDM-based wideband wireless communication system (e.g., an Institute of Electrical and Electronics Engineers (IEEE) 802.16e system) is installed. The conventional wideband wireless communication system supports only Mobile Stations (MSs) that have a single bandwidth for one FA. That is, the legacy system using the FA of 10 MHz has a structure that can support only MSs using an FA of 10 MHz. Therefore, in order to support a new MS having a greater bandwidth, such as an MS using an FA of 20 MHz, a new FA having a bandwidth of 20 MHz is necessary. However, with the advent of a ubiquitous information age, available frequency bandwidth has become insufficient, and therefore, it is difficult to allocate a new frequency bandwidth in order to support both the legacy system and the new system.
Accordingly, research on a frequency overlay technique, which uses a conventional multi-FA method without allocating a new frequency band, is being introduced. In the frequency overlay technique, previously used multiple FAs are simultaneously used to support a required new FA. For example, in a state where two FAs of 10 MHz are previously used, a service using an FA of 20 MHz can be provided without additional frequency allocation when the two FAs of 10 MHz are subjected to a frequency overlay process.
Therefore, in consideration of the introduction of the frequency overlay technique using multiple FAs, there is a need for a technique which distributes packets by using the multiple FAs and which supports QoS, in order to maintain a compatibility with the communication system.